From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 28 Oct 2004 08:40:04 -0700 From: "Martin J. Bligh" Subject: Re: NUMA node swapping V3 Message-ID: <1275120000.1098978003@[10.10.2.4]> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter , akpm@osdl.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: > Changes from V2: better documentation, fix missing #ifdef > > In a NUMA systems single nodes may run out of memory. This may occur even > by only reading from files which will clutter node memory with cached > pages from the file. > > However, as long as the system as a whole does have enough memory > available, kswapd is not run at all. This means that a process allocating > memory and running on a node that has no memory left, will get memory > allocated from other nodes which is inefficient to handle. It would be > better if kswapd would throw out some pages (maybe some of the cached > pages from files that have only once been read) to reclaim memory in the > node. > > The following patch checks the memory usage after each allocation in a > zone. If the allocation in a zone falls below a certain minimum, kswapd is > started for that zone alone. > > The minimum may be controlled through /proc/sys/vm/node_swap which is set > to zero by default and thus is off. > > If it is set for example to 100 then kswapd will be run on > a zone/node if less than 10% of pages are available after an allocation. I thought even the SGI people were saying this wouldn't actually help you, due to some workload issues? M. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org